Optical: systems and elements – Compound lens system – Microscope
Patent
1995-04-28
1998-01-13
Nguyen, Thong
Optical: systems and elements
Compound lens system
Microscope
350227, 350371, 350888, G02B 2106, G02B 2602, G02B 522
Patent
active
057085269
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an optical contrasting process for amplitude and/or phase objects to be microscopically examined.
RELATED ART
The microscopic examination of objects, in particular of living, uncolored cell and tissue materials or of colorless, transparent materials having object regions of different optical thickness requires contrast processes with the aid of which a better detectability of object structures can be achieved for the human eye.
Thus, it is known, for example, to achieve an "oblique illumination" in the illuminating section of a microscope by displacing the aperture diaphrag eccentrically from the optical (illuminating) axis. The disadvantages of these known contrasting processes consist in that they are difficult to reproduce, not cost effective to realize and have to be readjusted for each objective.
A further known process is the phase-contrast process. Contrast effects are produced in this case by inserting suitable optical means into the rear focal plane of the objective. Since pure phase objects change only the phase and not the amplitude of the light, while the human eye and the photographic plate respond to amplitude differences but not to phase differences, they remain invisible in the normal bright field image. With the aid of the known phase-contrast process, the phase differences caused by the (phase) objects are "converted" into amplitude differences and thereby rendered visible. Zernike realized that the phase of the illuminating light needed to be changed only by .lambda./4 in order to cancel the difference between a phase object and an amplitude object, that is to say to render phase structures visible just like amplitude structures. In practice, use is made of an annular platelet, the so-called "phase ring", which is positioned in the rear focal plane of the objective. The phase ring has a defined thickness and absorption. The application of a phase ring assumes that the illuminating light comes from an annular light source. This is achieved in structural terms by a diaphragm mounted in the region of the condenser. Since the diameter and the width of this diaphragm influence the illumination aperture, which must be at a specific ratio relative to the objective aperture, a known phase-contrast condenser contains a plurality of annular diaphragms which are conjugate with respect to the objectives and are arranged, for example, on a turret plate. The disadvantages thus consist in that a specially configured annular diaphragm must be present for each microscope objective and must be brought into the operating position. In addition, no "relief effect" can be achieved, and finally the process experiences disturbances, for example when examining liquid chambers.
Further known contrasting processes relate to the modulation contrast according to Hoffman. The high cost of production is disadvantageous, since special objectives have to be used which are not rotationally symmetrical. This process is, moreover, difficult to manipulate.
Finally, mention should be made of the interference contrast process which is, however, based on the use of optical polarization components of complicated crystal-optic orientations, which makes it very expensive in terms of production engineering and thus cost intensive. Moreover, it is not possible with this known process to examine objects which are located, for example, in plastic specimen containers, since plastic materials influence the polarization states.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to avoid the disadvantages of the known processes and to specify a combined optical contrasting process which permits a larger scope of application for all objects coming into consideration in conjunction with ease of operation, it being the case that relief contrasting takes place in addition to phase contrasting. The object consists, furthermore, in specifying a corresponding device in which no optical polarization components are used.
The object is achieved according to the invent
REFERENCES:
patent: 2637243 (1953-05-01), Marx
patent: 3743390 (1973-07-01), McCarthy et al.
patent: 5016981 (1991-05-01), Peppers et al.
E. Courtens et al., "Microscope Attachment for Improved Visibility of Weak Phase Objects", IBM Technical Disclosure Bulletin, vol. 22, No. 11, Apr. 1980, p. 5085.
T. Noda et al., "Separation of Phase and Absorption images in Phase-Contrast Microscopy", Journal of the Optical Society of America, vol. 9, No. 6, Jun. 1992, pp. 924-931.
Leica Mikroskopie und Systeme GmbH
Nguyen Thong
LandOfFree
Process and device for contrasting objects to be microscopically does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process and device for contrasting objects to be microscopically, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and device for contrasting objects to be microscopically will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-330856